Respirator



Dec. 20, 1966 R. w. WARREN 3,292,623

I RESPIRATOR Filed Feb. 24, 1964 /N VENTO/Z,

2/2 YMO/VD h! WAz/ZEN responsive to the pressure in the patients lungs.

United States Patent. O

3,292,623 RESPIRATOR Raymond W. Warren, McLean, Va., assignor to theUnited States of America as represented by the Secretary of the ArmyFiled Feb. 24, 1964, Ser. No. 347,092 1 Claim. (Cl. 128-203) Theinvention described herein may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment to me of any royalty thereon.

This invention relates to respirators and more particularly to novelpressure regulated device for cycling air to a persons lungs forbreathing purposes through the patients mouth and nose.

Objects of this invention include the provision of a novel, lightweight,inexpensive, no moving part, respirator which can efiiciently cycle airthrough a victims lungs by raising the pressure above and belowatmospheric pressure, and which will automatically adjust to the naturalrespiration of the patient.

The reasons for these objects may be readily appreciated by consideringthe usual emergency situation where a patient is unconscious, and hasapparently stopped breathing. The person may be a victim of drowning, ora battle casualty in a military situation. In these situations speed isessential. Since applicants device is lightweight, inexpensive, and hasno moving parts it may be widely distributed in the field at points ofpossible use. Since the respirator has no moving parts it will operatesatisfactorily after years of disuse.

By raising and lowering the pressure above and below atmospheric, themaximum exchange of air to the patients lungs can be accomplished.Further, since the respirator will automatically adjust to any feeblebreathing, there is no fighting between the respirator and the patient.

Applicants successful realization of the stated objects also makes thisinvention useful for persons with chronic respiratory disorders. In suchcases the lightweight, compact features permit some patients to becomeat least partially ambulatory by using this respirator. Further, theautomatic adjustment of the applicants novel respirator to the breathingof the patient is especially beneficial.

The stated objects of this invention, as well as other objects andfeatures of this invention, are achieved through the use of a bistable,pure fluid element. One output channel of the element is a respiratorychannel and the other channel is an exhaust channel. The respiratorychannel contains pressure sensitive control means which is When the lungpressure has built up to a predetermined amount, the air supply in therespiratory channel is stopped, and simultaneously the patients lungsare exhausted through this same channel until a predeterminedsubatmospheric pressure is reached. When the subatmospheric pressure isreached, the control means causes air to again enter the respiratorchannel.

FIG. 1 is a plane view of an embodiment of applicants novel respirator.

FIG. 2 is a partial sectional view showing the laminar construction, andcontrol adjustments.

In FIGURE 1 there is shown the respirator pump connected to a source ofcompressed air 11 with a mask 12 adapted to be applied over the face ofa patient.

The respirator pump 10 is essentially a bistable, lockon type, fluidamplifier. It has a fluid jet-forming nozzle 14, an expirating channel15, a respirating channel 16 and opposed control nozzles 17 and 18.

The characteristic of this type of fluid device, as is well understoodby those skilled in the art, is wall lockon. That is, a fluid jet formedin nozzle 14 and issuing from the nozzle 14a will become attached to,and lock on to either the wall 15a of expirating channel 15 or wall 16aof respirating channel 16. Attached to either the wall 15a or 16a is astable condition, and the fluid jet issuing from nozzle orifice 14a willremain attached until a control signal is received from control nozzles17 or 18.

In the respirating channel 16, there is a lung pressure sensing port 19.Connecting the lung pressure sensing port 19 and the control nozzle 18is afluid feed-back path .21.

The control nozzle 17 is connected to atmosphere via channel 22 and anadjusting valve 23. Feed-back line 21 has a similar adjusting valve 24.One embodiment of valve 23 is shown in FIGURE 2, which also illustratesa preferred laminar construction for the respirator 10.

The respirator may be constructed by bonding an upper flat plate 26,which may be made of a clear plastic if desired, to a lower plate 27which has the various channels and nozzles etched or machined on it,such as channel 22. The adjusting valve 23 may be merely a screw 28idapted to be screwed into the channel 22 to close it o In operation,the mask 12 is placed over the face of the patient while the air supply11 is turned on by means of a valve 31.

The air jet formed by nozzle 14 issuing from orifice 14a willinstantaneously impinge upon splitter 30, then quickly become attachedto either the wall 15a or 16a. If it is desired to insure that the jetwill initially flow into the respirator channel, the unit may begeometrically biased by placing the splitter 30 slightly to the right(toward nozzle 17) of the centerline of nozzle 14.

Assuming the air jet to be locked on the Wall 16a of respirator channel16, air will flow into the mask 12 and thence into the patients lungs.As the air fills the patients lungs, the pressure in the respiratorchannel 16 increases. This increased pressure in 16 is detected and fedback into control nozzle 18 via port 19 and channel 21.

When the pressure at the nozzle 18 exceeds a predeterminedamountsuificient to overcome the bias pressure at nozzle 17-the air jetis switched, attaches to wall 15a and issues from expirating channel 15.

Flow from the expirating channel entrains air from the respiratingchannel 16, lowering the pressure in this channel to below atmospheric.This lowered pressure in channel 16 helps to expel the air from thepatients lungs.

The reduced pressure in channel 16 is felt by the port 19 and fed backto control nozzle 18 via channel 21. When the pressure nozzle 18 hasreached a predetermined subatmospheric value, the pressure at nozzle 17,connected to atmosphere via channel 22, is sufficient to switch the airjet back into the channel 16, and becomes attached to the wall 16a. Airagain fills the patients lungs, and the above described cycle isrepeated.

As will be apparent to those skilled in the art, the frequency at whichthe respirator cycles can be adjusted by means of control valves 23 and24. That is, the dwell time, or time the air jet is in each channel 15or 16 may be adjusted to suit a patients natural respiratory rate bymeans of these valves 23 and 24.

Opening valve 23 alone tends to raise the pressure at nozzle 17increasing the time the air jet is in the respiratory channel 16.Conversely, closing valve 23 decreases the time the air jet is in therespiratory channel 16.

Closing valve 24 alone will tend to increase the time the fluid jetstays in respirator channel 16, and opening it tends to decrease thedwell time in respirator channel 16.

By properly adjusting the frequency of the respirator 10 to a valueslightly longer than the patients natural breathing rate, respirator 10can be used to assist a patient with a pulmonary disorder.. In thiscase. the patients arespirator control device connected to said sourceof 10 pressurized air and including a bistable fluid amplifier having anair jet nozzle, a respiratingchannel and expirating channel, saidchannels meeting and diverging from in front of said air jet nozzle, acontrol nozzle adjacent said jet nozzle, a closed feed-back pathincluding a port communicating with said respirating channel and saidcontrol nozzle, said feed-back path having a variable valve therein, abiasing nozzle adjacent said air jet nozzle and opposite said controlnozzle, said biasing means being in continuous communication withatmosphere and having means to modulate the communication of said abiasing nozzle and said atmosphere; and a mask attached to saidrespirator channel.

References Cited by the Examiner UNITED STATES PATENTS 2,536,435 1/1951FOX 12s 2 9 3,001,539v 9/1961 Hurvitz 137 s1.5 3,185,166 5/1965Hortonetal 137-81.5

OTHER REFERENCES Transactions American Society for Artificial InternalOrgans: A Blood Pump Powered and Controlled by a 15 Fluid AmplificationSystem, Barila et al., vol. VIII RICHARD A. GAUDET, Primary Examiner.

' C. F. ROSENBAUM, Assistant Examiner.

